Expandable intervertebral device, and systems and methods for inserting same

ABSTRACT

An expandable interbody device for implantation within an intervertebral space is provided, together with methods and tools for use therewith. The interbody devices include a leading first and trailing second bearing member configured to expand laterally via connecting portions disposed at the trailing end of the first being member and at least the leading end of the second bearing member. In some forms, the connecting portions have an arcuate configuration. The insertion tool is configured expand the interbody device by holding the first bearing member while shifting the second bearing member.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/509,725, filed Oct. 8, 2014, which claims the benefit of U.S.Provisional Application No. 61/888,387, filed Oct. 8, 2013, which areboth hereby incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

This invention pertains generally to implantable medical devices and, inparticular, to expandable implantable devices for intervertebral fusionand/or immobilization and systems and methods for inserting the same.

BACKGROUND OF THE INVENTION

Many people develop back pain during the course of their life due totraumatic injury, disease, or genetic defect. Typically, the patients'intervertebral discs, which support the spine, are damaged, causing thediscs to bulge or herniate. The disc bulge then impinges on the nervesof the spine and causes back pain. Surgeons often perform a discectomyto trim the disc bulge to alleviate back pain. However, the discectomymay structurally weaken the disc and often leads to subsequentstructural failure of the disc due to wear and aging, once again causingimpingement on the nerves of the spine and back pain. Surgicalimplantation of a medical implant device to structurally support andseparate the vertebrae may become desirable to end debilitating backpain and allow patients to regain normal life activities.

One known device for promoting fusion between adjacent vertebrae is anexpandable interbody device (IBD). Such devices are generally configuredto be inserted into the intervertebral space in a compact configuration,and then are expanded to an expanded configuration to restore theadjacent vertebrae to a desired spacing and provide stability at theaffected joint. Numerous mechanisms are known for expanding the lateralsize of an expandable IBD. It is also known to provide an IBD with oneor more openings in the top and bottom surfaces of the IBD forcontaining bone graft material to promote fusion between the vertebraeto stabilize the joint.

One disadvantage of known laterally expandable IBDs is that the lateralsize may be too large for insertion into the intervertebral disc spacefrom a variety of surgical approaches, limiting the versatility of theIBD. For example, some known expandable IBDs include opposing bodyportions that are connected via a pivot or rotary hinge at one end andare configured for insertion with the body portions side-by-side. Such aside-by-side configuration is less advantageous or too large for somesurgical approaches that have an especially narrow insertion opening.

Another perceived shortfall of known laterally expandable IBDs ismaintaining the IBD in the desired expanded position. Some knownlaterally expandable IBDs lack structure to keep the device fromexpanding further or retracting after being expanded initially by asurgeon. Because the intervertebral joint is subject to movement, it isdesirable for the expandable IBD to be restricted from shifting from thedesired expanded configuration after being positioned in theintervertebral space.

A further disadvantage of known expandable IBDs is that it is difficultor impossible to insert bone graft material into or adjacent theexpandable IBD after the IBD has been inserted into the intervertebralspace. While some expandable IBDs may be configured to hold bone graftmaterial for promoting fusion, once the device is expanded, in somecases there may not be sufficient bone graft material to fill the bonegraft cavity in the device such that sufficient bone graft material iskept in contact with the adjacent vertebral endplate to adequatelypromote bone ingrowth.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, an expandableintervertebral device for implantation within an intervertebral spacebetween adjacent vertebrae is provided. The implant device includesfirst and second bearing or spacer members that are expandable forshifting the members between a compact unexpanded configuration and anexpanded configuration. The spacer members are operably connected to oneanother via connecting portions of the first and second bearing membersto allow for shifting of the spacer members with respect to each other.The unexpanded configuration minimizes the lateral width of theintervertebral device to provide ease of insertion of the device intothe intervertebral space. The expanded configuration increases thelateral width of the intervertebral device to increase the stability ofthe joint and further promote fusion of the adjacent vertebrae byincreasing the area in which osteoconductive material may be positioned.Although the device may be configured to expand laterally in a range oforientations having a range of lateral widths between the unexpanded andfully expanded configurations, it is generally preferable to fullyexpand the device to maximize its lateral width. In one form, theinterbody device is configured such that insertion and expansion of thedevice may be accomplished with a single tool.

In one form, the spacer members have an elongate configuration eachhaving a longitudinal axis. In the compact, unexpanded configuration,the longitudinal axes are in substantial alignment with each other inorder to minimize the lateral width of the implant to promote ease ofinsertion. In one form of the expanded configuration, the leading end ofthe second bearing member is shifted away from the trailing end of thefirst bearing member so as to be spaced in a lateral direction from thetrailing end of the first bearing member. In general, the distance thatthe leading end of the second bearing member can be spaced in a lateraldirection from the trailing end of the first bearing member isconstrained in part by the size of the intervertebral space betweenadjacent vertebrae, including all or part of the annulus if the annulusis present. Accordingly, the bearing members are preferably configuredto limit how far the bearing members may be expanded to keep the bearingmembers from protruding from the intervertebral space. Theintervertebral device may include a resilient retaining clip forlimiting movement of the second spacer member with respect to the firstspacer member.

The first and second bearing members are interconnected by connectingportions that are configured to allow the bearing members to shiftbetween the compact and expanded configurations. In one form, theconnecting portions include mating projecting and recess portions of thefirst and second bearing members that are configured to allow theprojecting portion to slide in the recess portion as the second bearingmember is shifted relative to the first bearing member. In one form, theconnecting portions include a guideway of one of the spacer members anda guide member of the other spacer member with the guide member beingguided by the guideway as the spacer members are shifted between thecompact and expanded configurations. The guideway can be a channel ortrack and the guide member can be a projection received in the track. Inone form, the track is a cam track having an arcuate configuration sothat with the spacer members in the compact, substantially alignedconfiguration, a force exerted on one of the spacer members generallytoward the other spacer member will cause the guide member to slide inthe arcuate cam track for shifting the spacer members to the expandedconfiguration thereof.

The expandable intervertebral device may include a cam surface locatedon one of the first and second bearing members, and a cam followersurface on the other of the first and second bearing members. The camsurface is configured such that when the first and second bearingmembers are aligned along their respective longitudinal axes, applying alongitudinally directed force at the trailing end portion of the otherbearing member causes the cam follower surface to be cammed against thecam surface so that the leading end portion of the other bearing memberis shifted to be laterally offset from the one bearing member. The camsurface in one form is disposed on the trailing end portion of the firstbearing member, and the cam follower surface is located on the secondbearing member. The cam surface may extend transversely with respect tothe longitudinal axis of the one bearing member such that when alongitudinally directed force is applied at the trailing end portion ofthe other bearing member, the cam follower surface of the other bearingmember cams against the transversely extending cam surface so that theleading end portion of the other bearing member is shifted to belaterally offset from the one bearing member. In one form, the camsurface has an arcuate configuration such that the cam follower surfaceof the other bearing member follows an arcuate path defined by the camsurface when the cam follower surface is cammed against the cam surfaceto shift the leading end portion of the other bearing member to belaterally offset from the one bearing member. The cam follower surfaceof the other bearing member may extend from the leading end portion tothe trailing end portion thereof such that a portion of the cam followersurface at the leading end portion of the other bearing member engagesthe cam surface of the one bearing member when the first and secondbearing members are substantially aligned along their respectivelongitudinal axes, and another portion of the cam follower surface atthe trailing end portion of the other bearing member engages the camsurface of the one bearing member when the leading end portion of theother bearing member is shifted to be laterally offset from the onebearing member.

In another form, the first and second spacing members each have alongitudinal axis, bone-engaging outer surfaces, a distal leading end,and a proximal trailing end. Connecting portions of the first and secondspacer members are configured for allowing the first and second membersto stay connected while shifting relative to each other between a narrowinsertion configuration and an expanded configuration for stabilizingthe joint once inserted therein. In the unexpanded configuration, thespacer members are arranged end-to-end. More specifically, the trailingend or end portion of the first spacer member is engaged with theleading end or end portion of the second spacer member so that thelongitudinal axes of the first and second spacer members aresubstantially aligned or coaxial with one another. In the expandedconfiguration, the leading end of the second bearing member is shiftedaway from the first spacer member and the trailing end thereof so as tocreate a lateral gap between the leading end of the second spacer memberand the trailing end of the first spacer member such that the lateralsize of the device is increased relative to the narrow insertionconfiguration and the longitudinal axis of the second spacer member isoriented to be transverse to the longitudinal axis of the first spacermember. In this form, the first and second spacer members cooperate sothat the device in the expanded configuration has a V-configuration withthe leading ends of each spacer member laterally spaced apart from oneanother.

In one aspect, the first spacer member has an insertion tool engagingportion at the trailing end thereof and the second spacer member isconfigured to allow the insertion tool to extend through at least aportion thereof to allow access to the insertion tool engaging portion.The connecting portions may have an arcuate configuration. In anotheraspect, the connecting portions comprise mating channel portions of thefirst and second spacer members that are configured to allow the secondspacer member to shift along the mating channel portion of the firstspacer member. The mating channel portions may have an arcuateconfiguration to allow the second spacer member to shift along anarcuate path corresponding to the contour of the mating channelportions.

The bearing or spacer members may have a variety of configurations forpromoting insertion as well as boney ingrowth once inserted into theintervertebral space. To promote ease of insertion of the intervertebraldevice, the first spacer member preferably has a tapered leading end. Inone form, the first and second spacer members have an opening extendingalong the longitudinal axes thereof sized and configured to allow aguidewire pass through the spacer members so that the intervertebraldevice may be inserted into the intervertebral space via the guidewire.In one form, the first and second spacer members include outer surfaceseach configured to provide an opening between the respective outersurfaces for inserting osteoconductive material therein to promote boneyingrowth.

Preferably, the outer surfaces of the spacer members include projectionsto engage with the adjacent, facing vertebral surfaces to keep thespacer members from sliding with respect thereto in at least onedirection. In one form, the first spacer member includes projectionssuch as teeth that are configured to resist migration in at least onedirection, and the outer surface of the second spacer member comprisesprojections that are configured to resist migration in a differentdirection from the projections of the outer surface of the first spacermember. The projections on the spacer members may be configured to allowsliding along the vertebral surfaces when one of the spacer members isshifted from the unexpanded to the expanded configuration, but resistsliding along the path taken by the one bearing member in the oppositedirection.

Another form includes a system for implanting an interbody devicebetween adjacent upper and lower vertebrae. The system preferablyincludes a laterally expandable interbody device having interconnectedfirst and second implant members. The system also preferably includes aninsertion tool configured to hold the expandable interbody device. Theinsertion tool in one form comprises a proximal handle and a distalholding portion of the insertion tool for holding the first implantmember of the interbody device. The insertion tool also includes anactuator for engaging with the second implant member for shifting thesecond implant member at least in part laterally with respect to thefirst implant member for expanding the interbody device laterally. Inone form, a threaded recess is disposed in the body of the first implantmember for receiving a mating threaded rod of the distal holding portionof the insertion tool.

The second implant member preferably includes a lateral opening on oneside thereof such that the holding portion of the insertion tool may beinserted through the lateral opening to hold the first implant memberwhile allowing the second implant member to be shifted laterally whilethe first implant member is held by the holding portion. The actuatormay be configured to shift proximally and distally along or parallel toa longitudinal tool axis and matingly engage a proximal end of thesecond implant member to shift the second implant member from anunexpanded orientation to a laterally expanded orientation.

In yet another form, a method of inserting an expandable intervertebraldevice comprises the steps of preparing an intervertebral disc forimplantation of an interbody device, such as by creating an opening inthe annulus of the intervertebral disc or removing part or all of thedisc for insertion of the interbody device. The intervertebral devicemay be sized and configured to fit within the boundaries defined byKambin's triangle, and therefore the opening may be created within thoseboundaries. The method also may include the steps of inserting theinterbody device having interconnected first and second implant memberseach having a longitudinal axis into the intervertebral space with thelongitudinal axes of the implant members in substantial alignment withone another and the first implant member leading the second into theintervertebral space, holding the first implant member with an insertiontool, and expanding the interbody device to an expanded configurationwith the insertion tool by shifting the second implant member relativeto the first implant member along a path transverse to the longitudinalaxis of the first implant member while holding the first implant member.

In one form, expanding the interbody device comprises shifting thesecond implant member relative to the first implant member along anarcuate path transverse to the longitudinal axis of the first implantmember. In another form, the second implant member is shifted relativeto the first implant member until a retaining clip of the first memberengages in a recess in the second implant member. The step of insertingthe interbody device may include threading the interbody device on aguidewire and guiding the interbody device into the intervertebral spacetherewith. The step of shifting the second implant member relative tothe first implant member may include shifting a moveable ram member ofthe insertion tool along a longitudinal axis of the tool. In anotherform, the ram member is shifted linearly via rotation of a rotatableknob operably connected to the ram member.

Additional advantages and features of the invention will become apparentfrom the following description and attached claims taken in combinationwith the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

To understand the present invention, it will now be described by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of an expandable interbody device in acompact configuration in accordance with one aspect of the invention;

FIG. 1A is a schematic plan view of the interbody device of FIG. 1 inthe compact configuration;

FIG. 2 is a perspective view of the interbody device of FIG. 1 in afully expanded configuration;

FIG. 2A is a schematic plan view of the interbody device of FIG. 1 inthe fully expanded configuration;

FIG. 3 is top plan view of the interbody device of FIG. 2;

FIG. 4 is an exploded perspective view of the interbody device of FIG.1;

FIG. 5 is an alternate exploded perspective view of the interbody deviceof FIG. 1;

FIG. 6 is an exploded elevational view of the interbody body device ofFIG. 1;

FIG. 7 is an exploded perspective view of an insertion tool forinserting the interbody device of FIG. 1;

FIG. 8A is a perspective view of the interbody device of FIG. 1 held byan insertion tool in accordance with another aspect of the invention;

FIG. 8B is a longitudinal cross-sectional view of the device and tool ofFIG. 8A.

FIG. 9A is a perspective view of the interbody device of FIG. 1 held bythe insertion tool in the fully expanded configuration;

FIG. 9B is a longitudinal cross-sectional view of the device and tool ofFIG. 9B;

FIGS. 10A, 10B and 10C illustrate how the interbody device is connectedto the insertion tool;

FIG. 11 illustrates one approach for inserting the interbody device intothe intervertebral disc space with the insertion tool;

FIG. 12 illustrates expanding the interbody device in a lateraldimension within the intervertebral space via rotation of the tool knob;

FIG. 13 illustrates the step of removing the inserter from the interbodydevice and the intervertebral space after the interbody device has beenexpanded;

FIG. 14 is a perspective view of the insertion tool of FIG. 7;

FIG. 15 illustrates the insertion tool of FIG. 7 disassembled forcleaning;

FIGS. 16A-C illustrate the interbody device in a compact non-expandedorientation;

FIGS. 17A-C illustrate the interbody device in the fully expandedorientation;

FIGS. 18A and 18B illustrate the interbody device in the compact andexpanded orientations, respectively;

FIG. 19 shows the expanded interbody device implanted within theintervertebral space viewed in the transverse plane;

FIG. 20 is an exploded view of an anchor blade inserter in accordancewith another aspect of the invention;

FIG. 21 is a lateral view of the anchor blade inserter of FIG. 20;

FIG. 22 is a perspective view of the anchor blade inserter of FIG. 20holding an anchor blade in a first gripping orientation;

FIG. 23 is a perspective view of the anchor blade inserter in anintermediate partial release orientation; and

FIG. 24 is a perspective view of the anchor blade inserter in a fullrelease orientation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1-6 in accordance with one aspect of theinvention, an expandable interbody device 1 has first and second bearingor spacer members 10, 20 configured to be implanted in theintervertebral space between adjacent vertebrae (FIGS. 11-13 and 19).The first and second spacer members are movably connected to one anothervia connecting portions 10 a, 20 a that form a sliding interface 15between the spacer members 10, 20. The connecting portions 10 a, 20 aeach have an arcuate configuration to allow the members to be camminglyshifted along an arcuate path with respect to one another. In thisregard, the illustrated interface 15 is an arcuate, cam interface 15comprised of mating cam surfaces and cam follower surfaces that permitthe second bearing member 20 to be shifted from an aligned orientationshown in FIG. 1 to a laterally expanded orientation shown in FIG. 2 viaa longitudinally directed force along the axis L applied to the trailingend portion 23 of the second bearing member 20. As shown in FIG. 5, theconnecting portion 10 a includes a wedge-shaped, arcuate trailing endportion 11 having upper and lower channel portions 10 b, 10 c. Thechannels 10 b, 10 c are respectively formed between upper and lowerarcuate ridges 10 d, 10 e and arcuate side walls 10 f, 10 g.

As shown in FIGS. 1 and 5, the connecting portion 20 a of the secondspacer member is formed by upper and lower channels 20 b, 20 c thatinterengage with channels 10 b, 10 c and ridges 10 d, 10 e of the firstspacer member. The upper and lower channels 20 b, 20 c are in turnrespectively formed between upper and lower arcuate ridges 20 d, 20 eand arcuate side walls 20 f, 20 g, as seen in FIG. 5. Upper arcuateridge 10 d of the first spacer member slides within the upper channel 20b of the second spacer member, and similarly, upper ridge 20 d of thesecond spacer member slides within upper channel 10 b of the firstspacer member 10. In the same manner, lower arcuate ridge 10 e of thefirst spacer member slides within lower channel 20 c of the secondspacer member 20, while lower arcuate ridge 20 e of the second spacermember 20 slides within lower channel 10 c of the first spacer member10. Although connecting portions in the above described interbody devicehave an arcuate configuration, other configurations are alsocontemplated. Similarly, although interengaging channels areillustrated, other structure for connecting and shifting the spacermembers 10, 20 is also contemplated.

The expandable interbody device 1 is provided with a motion limitingfeature that is configured to limit the range of motion of the first andsecond spacer members with respect to one another. In the embodimentshown in the figures, the motion limiting feature takes the form of aretaining clip 30 disposed within the body of the first spacer member10. Retaining clip 30 has a curvilinear or s-shape configuration and isadapted to fit within a through-opening 10 h located near the trailingend of the first spacer member 10. The through-opening 10 h andretaining clip 30 are sized and configured to allow an engagementportion of the clip 30 to travel between engaged and disengagedpositions for respectively retaining the relative positions of the firstand second spacer members 10, 20 in the engaged position and allowingthe spacer members to shift with respect to one another in thedisengaged position. The clip 30 also includes a through opening 30 c toallow a guidewire or osteoconductive material to pass through the clip.Preferably, the through-opening is aligned with the guidewirethroughbore 30 q, described in more detail below. The retaining clip 30is preferably made from a resilient material, such as titanium orNitinol®, so that the clip 30 may be biased towards the engagedposition. In particular, the clip 30 is configured in such a way as tobe biased towards the connecting portion 20 a of the second spacermember 20.

The clip engagement portion is disposed at one end of the clip along anarm 31 thereof that includes upper and lower prongs 30 a, 30 b that areconfigured to protrude through openings 10 i, 10 j in the upper andlower arcuate side walls 10 f, 10 g of the first spacer member 10 suchthat they engage with the outer facing surfaces 20 h, 20 i of the upperand lower arcuate ridges 20 d, 20 e, respectively. Two pairs of stopsare disposed in the outer facing surfaces 20 h, 20 i of the secondspacer member to engage with the clip 30 at positions that correspondwith a compact insertion configuration and a fully expandedconfiguration, respectively.

As shown in FIGS. 4 and 6, the first pair of stops 20 j, 20 k arelocated adjacent the leading end of the second spacer member 20 and areconfigured to keep the second spacer member 20 from moving past itscompact insertion position in a proximal direction i.e., opposite to thedistal direction which is the direction the second spacer member 20takes to move to the expanded configuration. However, sloped surfaces 20l, 20 m are configured such that they do not provide a blocking surfacefor clip prongs 30 a, 30 b and consequently do not block movement of thesecond spacer member 20 relative to and along the first spacer member 10in the distal direction. When the second bearing member 20 is shifteddistally and laterally along the arcuate path, the clip arm 31 isdeflected with the clip prongs 30 a, 30 b urged against their bias forceto be deflected back through the openings 10 i, 10 j in the upper andlower arcuate side walls 10 f, 10 g by the sloped surfaces 20 l, 20 m,allowing second spacer member 20 to be shifted freely. Once the secondspacer member 20 is advanced distally and laterally along the arcuatepath such that prongs 30 a, 30 b are aligned with second pair of stops20 n, 20 p in the form of grooves adjacent the trailing end of thesecond spacer member 20, the clip arm 31 will resiliently rebound towardits undeflected orientation so that the prongs 30 a, 30 b are urgedunder their bias force into the grooves 20 n, 20 p. With prongs 30 a, 30b disposed in the grooves of stops 20 n, 20 p, the spacer members 10, 20are kept from moving with respect to one another in either directionalong the arcuate path of the interface 15. Alternatively, the stops 20n, 20 p could be configured similar to stops 20 j, 20 k, which blockmovement in only the distal direction to provide an outer limit.

Although the clip 30 is shown disposed in the first member 10, it couldbe alternatively configured to be disposed in the second member 20 andstops for limiting the motion of the spacer members could be provided onthe first spacer member 10. Other structures may be used for limitingmotion, as would be apparent to one of ordinary skill. Alternatively,the motion limiting features may have an alternate configuration, or beomitted altogether. For example, one or both sets of stops 20 j, 20 k,20 n, 20 p may be omitted. In another form, the clip 30 may be omittedand a motion limiting feature, such as an obstruction near the ends ofone or both of the channels 20 b, 20 c of the second bearing member 20,may be provided to keep the second spacer member 20 from beingoverextended or separated from the first spacer member 10. Likewise, themotion limiting features may be provided within the one or both of thechannels 10 b, 10 c of the first spacer member.

The first spacer member 10 has a conical or tapered leading end 10 k forpromoting ease of insertion into the intervertebral space. The firstbearing member 10 has opposing lateral sides 10 l, 10 m, and bone orendplate engaging outer surfaces 10 n, 10 o. The opposite, lateral sides10 l, 10 m each can have a generally flat configuration extendingparallel to the axis L1. The outer facing surfaces includethrough-openings 10 p, 10 h that extend completely through the body ofthe first spacer member 10 and may be used to hold osteoconductivematerial, such as a natural or synthetic bone graft.

The spacer members are cannulated to allow for insertion of guidestructure to guide the interbody device into the intervertebral space. Athroughbore 10 q extends along the longitudinal axis L₁ of the firstspacer member 10 from the distal leading end to the trailing end. Thethroughbore 10 q extends between the portion of the spacer member thatdivides the distal through-opening 10 p and the proximal through-opening10 h. Because the throughbore 10 q extends longitudinally through theentire length of the spacer member 10, it is suitable for insertion of aguidewire to help guide the interbody device 1 into the insertion site.As will be described in more detail herein, the various components ofthe interbody device 10 are configured to promote boney ingrowth intoand through the interbody device for stabilizing the joint afterimplantation of the device 1.

As shown in FIGS. 5 and 17C, the first spacer member 10 is provided witha tool engaging portion at its trailing end portion 11. The toolengaging portion includes a threaded recess 10 r which has an axisextending therethrough parallel to the longitudinal axis L₁ of thespacer member 10 configured for mating with a threaded tool, which willbe described in greater detail herein. The throughbore axis of thethroughbore 10 q is laterally offset from the axis of the threadedrecess 10 r so as not to cause interference between the guidewire andthe insertion tool 40. The tool engaging portion of the first spacermember 10 also includes notched or slotted portions 10 s on lateral sidewall 10 l, and slot 10 t opposite slot 10 s to provide an index formating with a corresponding portion of the insertion tool 40. The slots10 s, 10 t function to align the interbody device 1 on the tool 40 andprevent rotation of the interbody device 1 relative to the tool whileattaching to or detaching from the device 1.

The second spacer member body 20 has a general configuration thatresembles a circular segment with an open arcuate side 21 at which theconnecting portion 20 a is disposed and a generally flat lateral sidewall 20 q that extends generally parallel to the longitudinal axis L₂ ofthe second spacer member 20. The arcuate side 21 curves convexly oroutwardly away from the flat side wall 20 q. Upper and lower bone orendplate engaging outer surfaces 20 r, 20 s include through openings 20t, 20 u for promoting boney ingrowth. The arcuate side 21 of the secondspacer member has an open configuration such that the insertion tool maybe inserted at least partially between the upper and lower outersurfaces to be attached to the proximal trailing end of the first spacermember 10 while allowing the second spacer member to be shifted from itscompact insertion position to its expanded position. The inner surfaceof the second spacer member 20 is also configured to provide clearancefor a guidewire when the spacer members are in the compactconfiguration, the expanded configuration, as well as in intermediatepositions between the compact and expanded configurations. As shown inFIG. 6, the second spacer member 20 includes grooves 20 v disposed inthe inner surface for this purpose.

Referring next to the schematic views of FIGS. 1A and 2A, it can be seenthat the spacer members 10, 20 have a much narrower orientation in thecompact, insertion configuration of FIG. 1A than in the expandedconfiguration of FIG. 2A. More particularly, as illustrated the width,w, of the expandable interbody device 1 in the compact, insertionconfiguration thereof corresponds to the maximum width of each of thealigned elongate spacer members 10, 20. In this regard, the width wcorresponds to the lateral distance between the flat sides 10 m, 10 l ofthe spacer member 10 and the lateral distance between the flat side 20 qand the point 22 farthest laterally away therefrom along convexly curvedside 21. The flat sides 10 l, 20 q of the spacer members 10, 20 aregenerally aligned to be flush with one another and the flat side 10 m ofspacer member 10 is generally aligned with the point 22 along the curvedside 21 of the spacer member 20.

To shift the interbody device 1 from the compact configuration to theexpanded configuration, the spacer members 10, 20 are shifted relativeto each other. To this end, both of the spacer members 10, 20 could beshifted simultaneously, or one of the spacer members 10, 20 can beshifted while the other is held against shifting. The latter approach isdescribed herein, and specifically with respect to holding the spacermember 10 stationary while shifting the spacer member 20, although itwill be recognized that substantially the reverse operation could beperformed with the spacer member 20 being held while the spacer member10 is shifted.

As will be described further hereafter, insertion tool 30 advantageouslyexerts an axially directed force at a trailing end 23 of the spacermember 10. The axially directed force is exerted along the substantiallyaligned axes L1, L2 with the device 1 in the compact insertionconfiguration. This provides a mechanical advantage since the inputforce is applied at a location that is spaced from the cam interface 15between the interengaging structure of the channels 10 b, 10 c and 20 b,20 c of the spacer members 10, 20 as has been previously described.Further, the trailing end 23 of the spacer member 20 does notsignificantly shift off of or deviate from the axis along which theinput force is directed allowing the input force to be securelytransmitted to the spacer member 20 even as it starts to be advanced andturned along the arcuate cam path for being shifted to its expandedorientation. Instead, it is the leading end portion 24 of the spacermember 20 in engagement with the spacer member 10 with the device 1 inthe compact configuration that undergoes the greatest amount of shiftingaway from the axis L1 as the spacer member 20 is turned so that the axisL2 thereof is oriented to extend transversely to the axis L1 of thespacer member 10, as shown in FIG. 2A.

Once the interbody device 1 is shifted to its expanded configuration,the effective width, W, thereof is greatly increased over the width, w,in the compact, insertion configuration. By way of example and notlimitation, the effective width, W, in the expanded configuration can beapproximately 1.0 inch while in the compact configuration the effectivewidth, w, can be approximately 0.625 inch. In the expandedconfiguration, referring to the approximate midway point 22, over halfof the spacer member 20 including the entirety of the leading endportion 24 extends obliquely away from the arcuate, wedge-shapedtrailing end portion 11 of the spacer member 10. This also providesanother defined area, A, between the spacer members 10, 20 for receiptof bone growth material. The only effective loss of vertebral engagementarea in the widthwise direction of the interbody device 1 over thatprovided in the compact configuration is the small cross-hatched areashown in FIG. 2A adjacent the trailing ends of the spacer members 10,20. As is apparent, this is insignificant in size when compared to theextra area of engagement with the vertebral surfaces in the widthwisedirection of the interbody device 1 obtained by shifting the spacermember 20 to its expanded position as described above.

The outer surfaces 10 n, 10 o and 20 r, 20 s, of the spacer members 10,20 are preferably configured to resist movement once implanted and toresist expulsion from the intervertebral space. These outer surfacescomprise projections, such as teeth that are configured to resistmigration in at least one direction. The teeth on outer surfaces 10 n,10 o are oriented to resist movement in the proximal direction along thelongitudinal axis L₁ while the teeth on outer surfaces 20 r, 20 s of thesecond spacer member 20 are oriented to resist movement in a directiontransverse to the longitudinal axis L₂ of the second spacer member. Inparticular, the transverse direction corresponds generally to thearcuate path that the second spacer member 20 follows when shifted fromthe compact position to the expanded position. Accordingly, the teeth ofthe second spacer member 20 are effective to keep the second spacermember from shifting back from the expanded position to the unexpandedcompact position. With this configuration, the teeth simultaneouslyresist movement in a plurality of directions when the outerbone-engaging surfaces 10 n, 10 o, 20 r, 20 s of the spacer members arefirmly engaged with the adjacent vertebrae. Alternatively, theprojections may be configured to be direction-neutral, or may all beconfigured to resist movement in the same direction. Other structuresknown for fixing an implant in the intervertebral space may also beused, such as screws, fins, spikes, deployable or rotatable fixationmembers, adhesives, and the like.

Any known materials appropriate for implantation into the human body maybe used for the interbody device. However, it is preferred to use apolymer such as PEEK for the spacer members 10, 20. Coatings, such ashydroxyapatite (HA), may be used to promote bone growth to the surfacesof the interbody device 1. Other materials may be used, as is well knownin the art.

The interbody device 1 is preferably configured to allow for insertionof bone-growth or osteoconductive material, such as natural or syntheticbone grafts, including NANOSS® Bioactive 3D, an advanced bone graftcomposed of nano-structured hydroxyapatite granules and an openstructured engineered collagen carrier in a strip format, available fromPioneer Surgical Technology, Inc. Other biologics may be used, such asNANOSS® Bioactive or NANOSS® Bioactive Loaded, available from PioneerSurgical Technology, Inc., the latter being a flowable biologic materialdelivered via a syringe. Other known osteoconductive materials may alsobe used.

The bone-growth material may be inserted into the cavities of theintervertebral device 1 prior to insertion of the device into theintervertebral space. Alternatively, the bone-growth material may beinserted into the interbody device after insertion of the device intothe intervertebral space, either before or after expansion of the spacermembers. The trailing ends of the spacer members are sized andconfigured to provide an access opening that communicates with theinterior of the interbody device 1 for inserting osteoconductivematerial through the access opening. It is also contemplated thatosteoconductive material may be introduced in the area A between thefirst and second spacer members 10, 20 after they are shifted to anexpanded configuration, such as shown in FIGS. 2A and 3. A membraneattached to spacer members near the leading ends could be used tomaintain the osteoconductive material between the expanded spacermembers.

A method of inserting an expandable intervertebral device is shown inFIGS. 10A-13 and includes one or more of the steps of preparing anintervertebral disc for implantation of the expandable interbody device,attaching the expandable interbody device to the insertion tool,inserting the interbody device into the intervertebral space with theinsertion tool, expanding the interbody device into an expandedconfiguration with the insertion tool, removing the insertion tool, andoptionally inserting osteoconductive material into or adjacent to theinterbody device. In an alternative method, the expandable interbodydevice is cannulated along a longitudinal axis thereof so that thedevice may be threaded on a guidewire to guide the interbody device intoposition within the intervertebral space, with or without use of aseparate insertion tool.

An insertion tool 40 is provided for inserting the interbody device 1into an intervertebral space and for expanding the device afterinsertion. The interbody device 1 and insertion tool 40 may be sized andconfigured such that the device 1 may be inserted in many differentapproaches with respect to the spine, such as anterior, anterolateral,lateral, posterolateral, or posterior approaches. In one preferredmethod, the device and tool system are sized and configured to implantthe device 1 through Kambin's triangle. Kambin's triangle is defined asa right triangle over the dorsolateral disc. The hypotenuse of Kambin'striangle is the exiting nerve root, the base being the superior borderof the caudal vertebral body, and the height is the traversing nerveroot. (See Park et al., Kambin's Triangle Approach of LumbarTransforaminal Epidural Injection with Spinal Stenosis, Annals ofRehabilitation Medicine, Dec. 30, 2011.) With such an approach, theintervertebral disc is prepared for implantation by creating an openingin the annulus of the intervertebral disc for insertion of the interbodydevice within the boundaries defined by Kambin's triangle. Such anapproach is advantageous because the device may be implanted withoutneeding to remove any portion of the vertebral bone prior to insertion,simplifying the method of inserting the device and reducing trauma tothe patient. With all potential surgical approaches, the disc space maybe prepared by removing part or all of the intervertebral disc.

As shown in FIG. 7, the insertion tool 40 is comprised of a handleportion 42 at the proximal end of the tool, a distal holding portion 44for holding the interbody device 1, and an actuator for engaging withthe other implant member for shifting the other implant member withrespect to the one implant member. The distal holding portion 44 iscomprised of a stationary shaft 46 and a draw rod 48 with a threaded end48 a. The draw rod 48 is rotatably disposed within the stationary shaft46, and is rotatable via a rotatable knob 50 through which the draw rod48 is mounted. The draw rod 48 includes an indexed portion 48 b formatingly engaging with the knob 50. The stationary shaft 46 includes adistal alignment feature in the form of prongs 46 a, 46 b for engagingwith mating slots 10 s, 10 t. (See FIGS. 1 and 5.) The actuator includesa ram member 52 which is configured to shift distally and proximallyalong the stationary shaft 48 to engage with the trailing end of thesecond implant member 20 with the distal end 52 a of the ram member 52.As shown in FIG. 8B, the ram member 52 is driven via a threaded driveshaft 53 configured to shift axially along a tool axis LT. The threadeddrive shaft 53 is driven via rotary motion provided by rotation of thedrive knob 54, which is connected to the proximal end of the drive shaft53. The drive shaft 53 resides within a partially threadedthrough-opening 42 a of the handle 42. The stationary shaft 46 isconnected to the handle 42 via a cap member 56, which resides inthrough-opening 42 b in the handle 42. Cap member 56 threadingly engageswith stationary shaft 46 and also includes a through-opening 56 athrough which draw rod 48 extends and is rotatably supported.

FIGS. 8A, 8B show the operation of the tool 40 with the interbody device1 connected to the tool in the insertion configuration and FIGS. 9A, 9Bshow the tool 40 and interbody device 1 in the expanded configuration.In operation, the interbody device 1 is attached to the distal holdingportion 44 of the tool 40 with the interbody device in an unexpanded orcompact insertion configuration with the first and second implantmembers in substantial alignment, i.e., lined up end to end to minimizethe lateral width of the interbody device. Accordingly, substantialalignment means that the longitudinal axes L₁, L₂ of the first andsecond implant members should not meet at an angle of greater than 30degrees, and more preferably intersect at an angle less than 15 degrees,and still more preferably at an angle less than 5 degrees.Alternatively, substantial alignment may be defined as alignment of theaxes L1, L2 of the spacer members 10, 12 sufficient to allow theinterbody device to be inserted into the intervertebral space throughKambin's triangle while avoiding necessitating bone removal for thispurpose.

As shown in FIGS. 10B, 10C, the interbody device 1 is attached to thedistal holding portion 44 by inserting the prongs 46 a, 46 b of thedistal end of the stationary shaft into the slots 10 s, 10 t of thefirst implant member and threading the threaded end 48 a of the draw rod48 via clockwise rotation of the knob 50 into the threaded recess 10 rwithin the cavity of the first implant member 10. Once the interbodydevice 1 is attached to the insertion tool 40, the second implant member20 may be shifted to an expanded configuration via rotation of therotatable knob 54 in a clockwise direction. Rotation of the knob 54advances the ram member 52 longitudinally along the stationary shaft 46,causing the distal end of ram member 52 a to urge the second implantmember 20 distally along the arcuate path of the sliding interface 15.As the second implant member 20 is shifted along the arcuate path, thelongitudinal axis L₂ of the second implant member 20 shifts out ofsubstantial alignment with the longitudinal axis L₁ of the first implantmember 10 to extend more transversely relative thereto, i.e., the anglebetween the axes is increased. The second implant member 20 is advanceduntil the retaining clip 30 blocks further movement of the secondimplant member 20 via abutting engagement with the stops 20 n, 20 p, oralternatively until the distal end of the ram member 52 abuts the firstimplant member 10, preventing further advancement of the ram member 52relative to the spacer member 10. Once the second implant member 20 isadvanced to the desired expanded position, the interbody device 1 may beremoved from the tool 40 by rotating the knob 50 in a counterclockwisedirection to rotate the draw rod 48 until the threaded end 48 a is fullyretracted from the threaded recess 10 r of the first implant member.

In an alternative form, a tool for manipulating a surgical device isdisclosed. In one embodiment, the tool takes the form of an anchor bladeinsertion tool 100 for manipulating an anchor blade, and particularlyfor inserting an anchor blade 150 into a retractor blade, such as thatdisclosed in FIG. 5 of United States Published Patent Application2012/0232349, which is hereby incorporated by reference in its entirety.Although the tool is disclosed with reference to an anchor bladeinsertion tool, the tool has applicability in numerous applications, aswould be apparent to one of ordinary skill in the art.

As shown in FIGS. 20-24 the insertion tool 100 includes a distal handlemember 102, an actuator connected thereto in the form of a lever 104.The lever 104 is connected to a moveable lower shaft 106, which isoperable in conjunction with a stationary upper shaft 108 for grippingand releasing a portion of a surgical device, such as an opening 150 ain the proximal portion of anchor blade 150. The moveable lower shaft106 is shiftable proximally and distally along a longitudinal tool axisL between gripping and releasing configurations via shifting of thelever 104 from a distal or forward position to a proximal or rearwardposition, respectively. In other words, the lever 104 is pulled back torelease the anchor blade 150, and alternatively shifted forward tosecure the anchor blade 150 to the tool 100.

Each of the upper and lower shafts 108, 106 include a gripping portionat the distal end thereof in the form of a gripping hook 108 a, 106 a.The stationary distal gripping hook 108 a of the upper shaft 108 islocated distally along the tool axis L from the gripping hook 106 a ofthe moveable lower shaft 106. The gripping hooks 106 a, 108 a areconfigured to fit within a throughbore or other structure with opposingsurfaces that can be gripped via expansion of the gripping hooks apartfrom one another. Because the gripping hooks are configured to fitbetween opposing surfaces, the hooks face away from one another with thedistal gripping hook 108 a extending distally, and the proximal movablegripping hook 106 a extending proximally as shown in FIG. 21.

The moveable lower shaft 106 is connected to the lever 104 via a linkage110. The linkage is preferably comprised of a material with superelasticcharacteristics, such as NITINOL. The operation and characteristics ofsuch a superelastic linkage is described in United States PublishedPatent Application 2009/0234395, which is hereby incorporated byreference in its entirety. Such a linkage is preferred to transmitrelatively large amounts of tensile force with minimaldisplacement/strain of the linkage 110. The linkage 110 is connected tothe lever 104 via connecting members 112 and 114. Cylindrical connectingmember 114 is connected to the lever 104 via a pin 116 which extendsthrough a transverse through-opening 114 a. The through-opening 114 a issized and configured to accommodate arcuate movement of the pin 116 byallowing the pin 116 to travel normally (i.e. up and down) with respectto the longitudinal tool axis. The lever 104 includes opposing pivotportions 104 a, 104 b with recesses 104 c, 104 d that are configured tohold the pin 116 therebetween. The pin 116 is thereby held offset fromthe axis of rotation of the pivot portions 104 a, 104 b such that whenthe lever 104 is rotated clockwise about the pivot portions' axis ofrotation, the pin 116 rotates clockwise about the lever axis of rotationand experiences displacement towards the distal end of the tool. Thisreduces tension on the linkage 110 and also urges the linkage 110distally to cause a corresponding distal movement of the lower shaftmember 106, thereby moving the proximal gripping hook 106 a to movetowards the stationary gripping hook 108 a of the upper shaft 108 intothe releasing or loading configuration. To return the tool to thegripping configuration, the lever 104 is returned to the forwardposition as shown in FIG. 21. This pulls the lower shaft 106 proximallyand puts the linkage 110 in tension with an appropriate amount of forcesuitable for holding and manipulating the anchor blade 150.

While there have been illustrated and described particular embodimentsof the present invention, it will be appreciated that numerous changesand modifications will occur to those skilled in the art, and it isintended in the appended claims to cover all those changes andmodifications which fall within the true spirit and scope of the presentinvention.

What is claimed is:
 1. An expandable intervertebral device forimplantation within an intervertebral space between adjacent vertebrae,the expandable intervertebral device comprising: first and secondbearing members each having a longitudinal axis, opposing bone-engagingouter surfaces extending between a distal leading end and a proximaltrailing end; and connecting portions of the first and second bearingmembers configured for allowing the first and second members to stayconnected while shifting relative to each other between: (1) anunexpanded insertion configuration, wherein the trailing end of thefirst bearing member is engaged with the leading end of the secondbearing member and the longitudinal axes of the first and second bearingmembers are substantially aligned, and (2) an expanded configuration,wherein the leading end of the second bearing member is shifted awayfrom the trailing end of the first bearing member so as to be spaced ina lateral direction from the trailing end of the first bearing member.2. The expandable intervertebral device of claim 1, wherein the firstbearing member comprises an insertion tool engaging portion at thetrailing end thereof and the second bearing member is configured toallow an insertion tool to extend through at least a portion thereof toaccess the insertion tool engaging portion.
 3. The expandableintervertebral device of claim 1, wherein the connecting portions havean arcuate configuration.
 4. The expandable intervertebral device ofclaim 1, wherein the connecting portions comprise mating projecting andrecess portions of the first and second bearing members that areconfigured to allow the projecting portion to slide in the recessportion as the second bearing member is shifted relative to the firstbearing member.
 5. The expandable intervertebral device of claim 1,further comprising a resilient retaining clip operably connected to oneof the first and second bearing members for limiting the movement of thesecond bearing member with respect to the first bearing member.
 6. Theexpandable intervertebral device of claim 1, wherein the first andsecond bearing members comprise an opening extending along thelongitudinal axes thereof sized and configured to allow a guidewire topass through the bearing members.
 7. The expandable intervertebraldevice of claim 1, wherein the opposing outer surfaces of the firstbearing member comprise projections that are configured to resistmigration in one direction, and the opposing outer surfaces of thesecond bearing member comprise projections that are configured to resistmigration in a different direction from the projections of the opposingouter surfaces of the upper bearing member.
 8. A system for implantingan interbody device between adjacent upper and lower vertebrae,comprising: a laterally expandable interbody device havinginterconnected first and second bearing members; and an insertion toolconfigured to engage the expandable interbody device comprising: aproximal handle; a distal holding portion of the insertion toolconfigured for holding the first bearing member of the interbody device;and an actuator for engaging with the second bearing member for shiftingthe second bearing member laterally with respect to the first bearingmember for expanding the interbody device laterally.
 9. The system ofclaim 8, wherein the first bearing member further comprises a threadedrecess therein, and the distal holding portion of the insertion toolfurther comprises a threaded rod configured to matingly engage with thethreaded recess to attach the expandable interbody device to theinsertion tool.
 10. The system of claim 8, wherein the second bearingmember includes a lateral opening on one side thereof to allow thedistal holding portion to be inserted through the lateral opening tohold the first bearing member while further allowing the second bearingmember to be shifted laterally while the first bearing member is held bythe distal holding portion.
 11. The system of claim 8, wherein theactuator is configured to shift proximally and distally along alongitudinal tool axis and abbutingly engage a proximal end of thesecond bearing member to shift the second bearing member from anunexpanded orientation to a laterally expanded orientation with respectto the first bearing member.
 12. A method of inserting an expandableintervertebral device, comprising: preparing an intervertebral disc forimplantation of an interbody device; inserting the interbody devicehaving interconnected first and second bearing members each having alongitudinal axis into the intervertebral space with the longitudinalaxes of the bearing members in substantial alignment with one anotherand the first bearing member leading the second into the intervertebralspace; holding the first bearing member with an insertion tool; andexpanding the interbody device into an expanded configuration with theinsertion tool by shifting the second bearing member relative to thefirst bearing member along a path transverse to the longitudinal axis ofthe first bearing member while holding the first bearing member.
 13. Themethod of claim 12, wherein expanding the interbody device comprisesshifting the second bearing member relative to the first bearing memberalong an arcuate path transverse to the longitudinal axis of the firstbearing member.
 14. The method of claim 12, further comprising shiftingthe second bearing member relative to the first bearing member until aretaining clip of the first member engages with a mating recess in thesecond bearing member.
 15. The method of claim 12, wherein inserting theinterbody device includes threading the interbody device on a guidewireand guiding the interbody device into the intervertebral spacetherewith.
 16. The method of claim 12, wherein shifting the secondbearing member relative to the first bearing member comprises shifting amoveable ram member of the insertion tool along a longitudinal axis ofthe tool.
 17. The method of claim 12, wherein the step of preparing anintervertebral disc for implantation comprises creating an opening inthe annulus of the intervertebral disc for insertion of the interbodydevice within the boundaries defined by Kambin's triangle.